U.S. patent application number 14/320525 was filed with the patent office on 2015-12-31 for variable angle locking rotation correction plate.
The applicant listed for this patent is DePuy Synthes Products, LLC. Invention is credited to Thomas J. FISCHER, Adam HASHMI, Lynn KELLY, Daneen TOUHALISKY.
Application Number | 20150374423 14/320525 |
Document ID | / |
Family ID | 53776927 |
Filed Date | 2015-12-31 |
United States Patent
Application |
20150374423 |
Kind Code |
A1 |
HASHMI; Adam ; et
al. |
December 31, 2015 |
VARIABLE ANGLE LOCKING ROTATION CORRECTION PLATE
Abstract
A bone plate sized and shaped for fixation to one of a
phalangeal and metacarpal bone includes a head extending from a
first end to a second end and having an elongated curved plate hole
extending therethrough along a curved path from a first end to a
second end, a plate hole axis of the elongated curved plate hole
extending orthogonally from a top surface to a bone contacting
surface of the bone plate and a shaft extending from the head, the
shaft including an elongated shaft plate hole extending
therethrough and elongated in a direction extending orthogonal to a
central longitudinal axis of the bone plate, a plate hole axis of
the elongated shaft plate hole extending orthogonally from the top
surface to the bone contacting surface.
Inventors: |
HASHMI; Adam; (West Chester,
PA) ; KELLY; Lynn; (West Chester, PA) ;
TOUHALISKY; Daneen; (West Chester, PA) ; FISCHER;
Thomas J.; (Indianapolis, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DePuy Synthes Products, LLC |
Raynham |
MA |
US |
|
|
Family ID: |
53776927 |
Appl. No.: |
14/320525 |
Filed: |
June 30, 2014 |
Current U.S.
Class: |
606/281 ;
606/280 |
Current CPC
Class: |
A61B 17/8061
20130101 |
International
Class: |
A61B 17/80 20060101
A61B017/80 |
Claims
1. A bone plate sized and shaped for fixation to one of a
phalangeal and metacarpal bone, comprising: a head extending from a
first end to a second end and having an elongated curved plate hole
extending therethrough along a curved path from a first end to a
second end, a plate hole axis of the elongated curved plate hole
extending orthogonally from a top surface to a bone contacting
surface of the bone plate; and a shaft extending from the head, the
shaft including an elongated shaft plate hole extending
therethrough and elongated in a direction extending orthogonal to a
central longitudinal axis of the bone plate, a plate hole axis of
the elongated shaft plate hole extending orthogonally from the top
surface to the bone contacting surface.
2. The bone plate of claim 1, wherein the elongated curved plate
hole is positioned on a first side of the central longitudinal
axis.
3. The bone plate of claim 2, wherein the head includes first and
second variable angle plate holes extending therethrough.
4. The bone plate of claim 3, wherein the first and second variable
angle plate holes are open to one another.
5. The bone plate of claim 4, wherein the first and second variable
angle plate holes are positioned on a second side of the central
longitudinal axis.
6. The bone plate of claim 1, wherein the head further comprises a
first notch on the first end between the elongated curved plate
hole and the first variable angle plate, the first notch formed as
an indentation on an outer wall of the bone plate sized.
7. The bone plate of claim 6, wherein the head further comprises a
second notch on a first side wall of the bone plate between the
first and second variable angle plate holes.
8. The bone plate of claim 1, further comprising a reduced diameter
neck between the head and the shaft, a diameter of the being
reduced relative to adjacent portions of the head and shaft.
9. The bone plate of claim 3, wherein the shaft further comprises
third, fourth and fifth variable angle plate hole extending
therethrough and positioned between the head and the elongated
shaft plate hole.
10. The bone plate of claim 9, wherein the third, fourth and fifth
plate holes are staggered about the central longitudinal axis so
that third and fifth plate hole are located on a first side of the
central longitudinal axis and the fourth plate hole is located on a
second side of the central longitudinal axis.
11. The bone plate of claim 2, wherein the elongated shaft plate
hole is centered about the central longitudinal axis.
12. The bone plate of claim 9, further comprising sixth and seventh
variable angle plate holes extending therethrough and positioned
between the elongated shaft plate hole and the second end of the
bone plate.
13. The bone plate of claim 12, wherein the sixth and seventh plate
holes are centered about the central longitudinal axis.
14. The bone plate of claim 1, wherein the shaft includes a
plurality of shaft notches formed in first and second side walls
thereof, the shaft notches defining reduced width regions of the
shaft.
15. The bone plate of claim 1, further comprising a plurality of
undercuts extending into the bone contacting surface of the bone by
a depth less than a thickness of the bone.
16. The bone plate of claim 1, further comprising a tapered region
extending around a periphery of the bone plate to reduce a profile
thereof.
17. The bone plate of claim 1, wherein a bone contacting surface of
the head is contoured to conform to the anatomy of a dorsal surface
of a head of the bone.
18. A method for bone fixation, comprising: positioning a bone
plate over a dorsal surface of a one of a phalangeal and metacarpal
bone, the bone plate extending from a first end having a head to a
second end having a shaft; inserting a first fixation element into
an elongated curved plate hole extending through the head by a
first depth, wherein the elongated fixation element hole extends
along a curved path from a first end to a second end, a plate hole
axis of the elongated curved plate hole extending orthogonally from
a top surface to a bone contacting surface of the bone plate;
sliding the bone plate over the bone within a first range of motion
limited by a length of the elongated curved plate hole to a desired
location over the bone; inserting a second fixation element into an
elongated shaft plate hole extending through the shaft and
elongated in a direction extending orthogonal to a central
longitudinal axis of the bone plate; sliding the bone plate over
the bone within a second range of motion limited by a length of the
elongated shaft plate hole to a desired location over the bone; and
inserting a third fixation element into the second fixation element
hole to lock the bone plate over the bone.
19. The method of claim 18, further comprising the step of rotating
the bone plate about the first fixation element to the desired
location prior to insertion of second and third fixation elements
thereinto.
20. The method of claim 18, further comprising the step of
tightening the first fixation elements into the elongated curved
plate hole to a second depth greater than the first depth to lock
the bone plate to the bone.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to bone plates for
the fixation of fractures of the hand and methods of coupling these
plates to bone,
BACKGROUND
[0002] Many current systems and methods for the fixation of
fractures, especially fractures in the hand, are limited in the
placement and orientation of plates over the bone. For example, a
surgeon or other user may be required to select a final placement
position of the bone plate prior to beginning a bone reduction
procedure. Such plates may prevent the surgeon from selecting the
most optimal implantation location for the bone plate. Furthermore,
such plates may prevent the fixation of a fractured or otherwise
damaged bone in a manner to fully correct the alignment of one or
more bone fragments. Rather, such fragments must be brought as
close to a final configuration as possible prior to the placement
of the bone plate thereover, which may result in subsequent
misalignment as the bone plate is being secured to the bone.
Rotational misalignments are especially problematic due to crossing
and scissoring of the digits when a full flexion of the fingers
(e.g., making a fist) is attempted. Even minor rotational errors in
the fingers may have to be surgically corrected after a fracture
has healed. Furthermore, this method of insertion may also
compromise adjacent soft tissue.
SUMMARY OF THE INVENTION
[0003] The present invention is directed to A bone plate sized and
shaped for fixation to one of a phalangeal and metacarpal bone,
comprising a head extending from a first end to a second end and
having an elongated curved plate hole extending therethrough along
a curved path from a first end to a second end, a plate hole axis
of the elongated curved plate hole extending orthogonally from a
top surface to a bone contacting surface of the bone plate and a
shaft extending from the head, the shaft including an elongated
shaft plate hole extending therethrough and elongated in a
direction extending orthogonal to a central longitudinal axis of
the bone plate, a plate hole axis of the elongated shaft plate hole
extending orthogonally from the top surface to the bone contacting
surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Several embodiments of the invention will be described in
the following by way of example and with reference to the
accompanying drawings in which:
[0005] FIG. 1 shows a top view of a bone fixation plate according
to a first exemplary embodiment of the invention;
[0006] FIG. 2 shows a bottom view of the bone fixation plate of
FIG. 1;
[0007] FIG. 3 shows a perspective view of the bone fixation plate
of FIG. 1; and
[0008] FIG. 4 shows a side view of the bone fixation plate of FIG.
1.
DETAILED DESCRIPTION
[0009] The exemplary embodiments may be further understood with
reference to the following description and the appended drawings,
wherein like elements are referred to with the same reference
numerals. The exemplary embodiments relate to apparatus and methods
for the treatment of fractures and, in particular, to devices for
fixing fractures of the metacarpals and phalanges. Exemplary
embodiments describe a bone fixation plate having a head at a first
end with an elongated shaft extending therefrom to a second end.
The head of the exemplary bone plate includes first and second
variable angle fixation holes along a first side thereof. The head
also includes an elongated curved hole extending along a second
side thereof. The elongated curved hole permits rotation and
angulation of the bone plate about a cortex screw inserted
therethrough as will be described in more detail below. The shaft
includes third, fourth and fifth plate holes staggered about a
central longitudinal axis of the bone plate and an elongated plate
hole extending along an axis orthogonal to the central longitudinal
axis. As will be described in greater detail later on, the
elongated hole further aids in optimally positioning the plate over
a target portion of the bone. The shaft further may comprise sixth
and seventh variable angle locking holes at a second end thereof.
The sixth and seventh holes are aligned with the central
longitudinal axis. A bone contacting surface of the head has a
curvature selected to conform to a curvature of a dorsal surface of
a bone to ensure flush seating of the plate thereover. As will be
described in greater detail later on, the exemplary curved and
elongated plate holes permit the adjustment of rotation and
angulation of the bone plate prior to a final fixation of the bone
plate to the bone.
[0010] As shown in FIGS. 1-4, an exemplary bone plate 100 has a
head 104 at a first end 102 thereof and a shaft 108 extending
therefrom generally along a central longitudinal axis 110 to a
second end 106. The head 102 is includes first and second variable
angle plate holes 112, 114 extending therethrough from a bone
contacting surface 116 to an upper surface 118, the first and
second plate holes 112, 114 being open to one another at an opening
111. Trajectories for plate hole axes 113, 115 of the first and
second plate holes 112, 114 are selected to capture common fracture
patterns while avoiding the articular surface of the bone and
minimizing interference with adjacent collateral ligaments. As
shown in FIG. 4, the plate hole axes 113, 115 may be generally
orthogonal to the top surface 118 while the variable angle feature
of the plate holes 112, 114 permits a surgeon to vary an angle at
which screws are inserted through these holes (relative to the hole
axes) to optimize these trajectories to suit the anatomy of a
particular patient.
[0011] The head 104 further comprises an elongated curved plate
hole 122 extending from a first end 124 to a second end 126 along a
curved arc-shaped axis 123. A length of the plate hole 122 between
the first and second ends 124, 126 is greater than a diameter of
the first and second plate holes 112, 114. A width of the plate
hole 122 is equivalent to a diameter of the first and second plate
holes 112, 114. A length of the plate hole 122 may be equivalent to
or slightly longer than a length of a combination of the first and
second plate plates holes 112, 114. The first and second plate
holes 112, 114 and the curved plate hole 122 may be sized, shaped
and positioned along the head 104 to maximize the amount of area
for screw placement while minimizing the foot print of the head 104
and maintaining strength of the plate 100.
[0012] A radius of curvature of the plate hole 122 may be, for
example, 3.75 mm or 5.0 mm, although other values are depicted
within the scope of the invention. A center from which the radius
of curvature of the plate hole 122 may be measured may be located
through, for example, the first plate hole 112. The curved plate
hole 122 follows a banana-like curvature, curving toward the
central longitudinal axis 110 so that the first end 124 is further
from the axis 110 than is the second end 126. The exemplary
curvature of the elongated curved plate hole 122 permits the bone
plate slid along the curve about a bone screw inserted
therethrough. Specifically, the bone screw (not shown) may be
inserted into the elongated curved plate hole 122 at a position
selected to capture one or more bone fragments. The bone screw (not
screw) may be inserted through the bone plate 100 and bone (not
shown) to a first depth permitting the bone plate 100 to be movable
about the bone screw. Subsequent sliding of the bone plate 100
along the axis 123 moves the bone plate 100 along a curved path
corresponding to the path 123 as the bone plate 100 is moved in
first and second directions along the central longitudinal axis
110. Furthermore, a surgeon or other user may rotate the bone plate
100 about the bone screw (not shown) received in the elongated
plate hole 122 to achieve a desired orientation over the bone, as
will be described in greater detail with respect to the exemplary
method below. As phalange and metacarpal fractures typically result
in a breakage of the "head" or "condyle" to a smaller fragment, the
curved plate hole 122 located in the head 104 permits the surgeon
or other user to affix the head 104 of the plate 100 to that
smaller fragment first, and then would have the ability to rotate
the plate to fit the shaft.
[0013] An outer surface of the head 104 substantially follows a
position of the first, second and elongated plate holes 112, 114,
122. Specifically, a first side wall of the head 128 of the head
104 follows a curved path corresponding to a curvature of the
elongated plate hole 122. A second side wall 130 of the head 104 is
also curved to conform to the shape of the first and second plate
holes 112, 114, the size and curvature of the second wall 130 being
formed so that a minimum clearance is formed about the first and
second plate hole 112, 114. A first notch 132 is formed on the
second side wall 130 of the head 104 and has a substantially
rounded shape. The first notch 132 is formed as a cutout extending
into the second side wall 130 and has a shape corresponding to an
arc of a circle. In another embodiment, the first notch 132 may
have a non-circular shape (e.g., oblong, etc.) without deviating
from the scope of the invention. The first end 102 of the bone
plate 100 also comprises a second notch 134 positioned between the
first and elongated plate holes 112, 122, the second notch 134 also
having a substantially rounded shape. In one embodiment, the second
notch 134 has a radius of curvature of 1.5 mm or 2.0 mm. However,
this radius of curvature is exemplary only and other values may be
used without deviating from the scope of the invention. The second
notch 134 is centered with respect to the central longitudinal axis
110 of the bone plate. In another embodiment, the second notch 134
may have a non-circular shape (e.g., oblong, etc.) without
deviating from the scope of the invention. The first and second
notches 132, 134 also effectively reduce an outer profile of the
bone plate 100 without compromising the structural integrity
thereof.
[0014] The bone-contacting surface 116 of the bone plate 100 is
curved to conform to the curvature of a target dorsal surface of a
metacarpal or phalangeal bone. In one embodiment, the
bone-contacting surface 116 of the head 104 includes curvatures of
varying radii. A predetermined length of the head 104 at the first
corner 122 may be curved downward toward the bone in a direction
toward a palmar surface of the bone in an implanted configuration.
This downward curvature aids in reduction of the fracture.
[0015] A reduced diameter neck 136 separates the head 104 from the
shaft 108. The shaft 108 extends distally from the neck 136 to the
distal end 106 and includes third, fourth, fifth, sixth and seventh
variable angle plate holes 138, 140, 142, 144, 146. In one
embodiment, trajectories 139, 141, 143, 145, 147 of the third,
fourth, fifth, sixth and seventh place holes 138, 140, 142, 144,
146 are orthogonal to a plane housing the bone plate 100 while the
variable angle features thereof permit a surgeon to vary the angles
at which screws are inserted therethrough to optimize these
trajectories to suit the anatomy of a particular patient. Thus, the
trajectories 139, 141, 143, 145, 147 may assume any path selected
to lockingly engage the bone without extending through an opposing
cortical surface thereof. The third, fourth and fifth plate holes
138, 140, 142 are staggered about the central longitudinal axis 110
so that central axes 139, 141, 143 thereof are offset relative to
the axis 110. The staggered shaft portion of the plate 100
increases plate strength and allows for distribution of bone screws
over a larger surface area of the bone to capture fracture
fragments in a comminuted shaft, as those skilled in the art will
understand. Specifically, the third and fifth plate holes 138, 142
are offset in a first direction toward a first side wall 148 of the
shaft 108. Specifically, the third and fifth plate holes 138, 142
extend away from the axis 110 in the first direction by a distance
greater than any other portion of the shaft 108. In a preferred
embodiment, the central axis 139 of the third plate hole 138 is
separated from the axis 110 by a distance D.sub.1 and the central
axis 143 of the fifth plate hole 142 is separated from the axis 110
by a distance D.sub.2, wherein D.sub.1 is greater than D.sub.2. The
fourth plate hole 140 is offset in a second direction toward a
second side wall 150 of the shaft 108 so that a distance D.sub.3 is
formed between a central axis 141 of the fourth plate hole 140 and
the axis 110. The distances D.sub.2 and D.sub.3 may be
substantially equivalent to one another. The central axes 141, 143
of the fourth and fifth plates holes 140, 142, respectively, may be
closer to the axis 110 than the central axis 139 of the third plate
hoe 138 since the phalanges and metacarpals become thinner towards
a central portion thereof. It will be understood by those of skill
in the art, however, that D.sub.1 is not required to be greater
than D.sub.2 and D.sub.3, so long as the third, fourth and fifth
holes 138, 140, 142 are positioned through the plate 100 so that,
when the plate 100 is positioned along a bone, the third, fourth
and fifth holes 138, 140, 142 extend along a portion of the bone.
It will also be understood by those of skill in the art that
although the exemplary embodiment shows the third and fifth holes
138, 142 as offset from the axis 110 in the first direction towards
the first side wall 148 and the fourth plate hole 140 is offset
from the axis 110 in the second direction toward the second side
wall 150, a direction in which the third, fourth and fifth holes
138, 140, 142 are offset may also be reversed. In particular, the
third and fifth holes 138, 142 may be offset in the second
direction while the fourth hole 140 may be offset in the first
direction.
[0016] The shaft 108 also includes an elongated hole 152 elongated
in a direction orthogonal to the longitudinal axis 110. The
elongated hole 152 is centered about the central longitudinal axis
110, a trajectory 153 thereof extending orthogonally from the bone
contacting surface 116 to the top surface 118. An axial length of
the elongated hole 130 is at least larger than a diameter of the
first through seventh plate holes 112, 114, 138, 140, 142, 144, 146
while a width of the elongated hole 152 may be equivalent to the
diameter of first through seventh plate holes 112, 114, 138, 140,
142, 144, 146. In a preferred embodiment, the first through seventh
plate holes 112, 114, 138, 140, 142, 144, 146 are 1.5 mm variable
angle holes. However, in another embodiment, one or more of the
first through seventh plate holes 112, 114, 138, 140, 142, 144, 146
may be formed as standard locking holes having a diameter of 2.0
mm. Still further, it is noted that any other diameter of the holes
may be used without deviating from the scope of the invention to
conform to the requirements of a particular procedure. As will be
described in greater detail below with respect to the exemplary
method, the elongated hole 130 permits a surgeon or other user to
slide the bone plate 100 over the bone within a predetermined range
(i.e., corresponding to a length of the elongated hole 152) prior
to locking the bone plate 100 in place. In one embodiment, the
elongated hole 130 may allow for a movement of the bone plate along
an axis 154 while also permitting rotation of the bone plate 100
therearound. Specifically, a surgeon or other user may insert a
first bone screw into one of the elongated holes 122, 152 to affect
a position of the bone plate 100 over the bone, as will also be
described in greater detail later. The exemplary elongated plate
hole 152 extends orthogonally through the bone plate from the upper
surface 118 to the bone contacting surface 116. The elongated holes
122, 152 bypass the need for a guidewire to position the bone plate
100 over the bone. Rather, since the bone plate 100 is adjustable
relative to a bone screw inserted through the elongated hole 122,
152, a surgeon or other user may use the elongated holes 122, 152
as a guide when positioning the bone plate 100 over the bone.
[0017] The sixth and seventh holes 144, 146 are axially aligned and
symmetrically positioned relative to the central longitudinal axis
110.
[0018] The bone-contacting surface 116 of the shaft 108 is curved
along the longitudinal axis 110 to conform to the substantially
cylindrical shape of the target portion of the bone over which the
shaft 108 will be seated. In one embodiment, the length of the
shaft 108 may include a single uniform curvature. In another
embodiment, the bone contacting surface 116 of the shaft 108 may
include a plurality of curves selected to ensure that the shaft 108
is seated flush over the bone.
[0019] The shaft 108 also includes a plurality of first webbed
portions 158 extending along the first side wall 148 between each
of the holes 138, 142, 148, 144, 146 and a plurality of second
webbed portions 160 extending along the second side wall 150
between each of the holes 114, 140, 152, 144, 146. The first and
second webbed portions 158, 160 are formed as notches extending
into the width of the bone plate 100 reducing a profile thereof
while maintaining the structural integrity of the bone plate 100.
The first and second webbed portions 158, 160 as well as the first
and second notches 132, 134 are sized to maintain a minimum desired
clearance remains around the boundary of each of the plate holes of
the bone plate 100. An outer periphery of the bone plate 100 may
include a rounded taper to further reduce the profile as would be
understood by those skilled in the art.
[0020] The bon-contacting surface 116 of the bone plate further
comprises a plurality of undercuts 162, 164, 166, 168, 170, 172
positioned between plate holes to permit bone ingrowth while also
imparting additional flexibility to the bone plate 100 to permit a
surgeon to further bend the bone plate 100 to a desired curvature
to more closely match the anatomy of a patient's bone and promote
healthier bone ingrowth. The undercuts 162, 164, 166, 168, 170, 172
are formed as cutouts extending into the bone plate 100 from the
bone-contacting surface 116 by a depth smaller than a thickness of
the bone plate 100. In a preferred embodiment, a shape of the
cutouts is a half-cylindrical segment, although other shapes (e.g.,
rectangular, etc.) may be used without deviating from the scope of
the invention. First, second and third undercuts 162, 164, 166 are
angled with respect to the axis 110 to in accordance with a
position of the third, fourth and fifth plate holes 138, 140, 142.
Specifically, the first undercut 162 encloses an angle of
105.degree. relative to the axis 110. The second undercut 164
encloses an angle of 60.degree. relative to the axis 110. The third
undercut 166 encloses an angle of 120.degree. relative to the axis
110. Fourth, fifth and sixth undercuts 168, 170, 172 extend
orthogonal to the axis 110.
[0021] The exemplary bone plate 100 is configured for use in
indirect reduction techniques for crushes, multi-fragmented and/or
periarticular fractures of the metacarpals and phalanges. In
accordance with an exemplary method according to the invention, the
bone plate 100 is positioned over a target dorsal surface of a bone
10 in a target orientation so that the elongated curved plate hole
112 is positioned adjacent a far side of a fracture near a section
of intact bone. The surgeon or other user approximates the desired
position of the bone plate 100 over the bone 10. A first cortex
screw (not shown) is then inserted through the elongated curved
hole 122 and into the bone 10 to a first depth sufficient to hold
the bone plate 100 over the bone 10 while still permitting movement
of the bone plate 100 relative to the bone 10. The bone plate 100
is then slid along the axis 123 about the first cortex screw (not
shown) received in the hole 122 until a desired position has been
reached. The first cortex screw (not shown) may be tightened and
loosened a plurality of times during this repositioning. A second
cortex screw (not shown) is then inserted into the elongated hole
152 to the first depth sufficient to hold the bone plate 100 over
the bone 10 while still permitting movement of the bone plate 100
relative to the bone 10. The bone plate 100 is then repositioned
along the axis 154 to a desired final configuration. The first and
second cortex screw (not shown) may be tightened and loosened a
plurality of times during the above repositioning. The exemplary
bone plate 100 according to the invention allows for an adjustment
of rotation and angulation of the bone plate 100 prior to a
permanent fixation thereof over the bone. Once the target position
has been reached, additional screws (not shown) may be inserted
into any of the remaining plate holes 112, 114, 138, 140, 142, 144,
146. The exemplary system and method according to the invention
bypasses the need for pre-drilling holes in the bone. Rather, once
the target position has been achieved, bore holes are drilled
through any of the plate holes 112, 114, 138, 140, 142, 144, 146
and into the bone 10 at a desired angle selected to conform to the
requirements of the particular bone. In contrast, present bone
fixation systems require the insertion of a guidewire into the bone
prior to the placement of the bone plate over the bone, thus
requiring that a final position of the bone plate 100 be selected
prior to the placement of the bone plate over the bone. This method
may lead to reduced accuracy in placement, especially in the
fixation of phalangeal bones where even the smallest deviation,
(e.g., in millimeters) from a correct position may lead to less
than optimum fixation. The exemplary bone plate 100, on the other
hand, permits adjustment of the position of the bone plate 100 even
after the bone plate 100 has been initially secured to the bone,
thereby ensuring that the final position of the bone plate 100
captures all fragments of the bone 10 while avoiding interference
with ligaments, tendons or other tissue.
[0022] It will be appreciated by those skilled in the art that
various modifications and alterations of the disclosed embodiments
may be made without departing from the broad scope of the
invention. Some of these have been discussed above and others will
be apparent to those skilled in the art.
* * * * *